The present invention relates to a non-linear optical film having a non-linear optical characteristic for use in a device for changeover of a signal optical path or for turning-ON/OFF of a signal.
The conventional switching of light information has required a photo-electric conversion means for once converting light information into electrical information and an electro-photo conversion means for reversely converting the electrical information into light information at each relay point. In order to build up a higher-speed light communication system, optical switches (mechanical type optical switches, planar light waveguide type optical switches, mirror type optical switches, bubble type switches, etc.) for directly switching the light information have been developed as described in “Nikkei Electronics” No. 8, Jan. 29, 2000 (non-patent document 1).
For the purpose of developing an optical switch capable of much higher-speed switching, there has been an attempt to achieve a further higher-speed response performance by use of a material having a non-linear optical characteristic. It has been reported that a high-speed and high non-linear optical characteristic can be attained by use of a vitreous thin film in which semiconductor particulates of a ferromagnetic oxide are dispersed, by Japanese Patent Laid-open Nos. 5-224262 (patent document 1) and 2002-72264 (patent document 2).
The optical switch using the thin film as above-mentioned has posed a problem that at the time of changeover of a signal optical path, absorption and/or scattering due to the thin film occurs, causing the attenuation of the signal.